The total double-cut 1-loop amplitude \(\mathcal {C}^{(1)}_{0 \ n.a.}\)  was earlier computed in [1]}, making use of the results of [2]}, [3]}.
Therefore, also in this case, our result differs from the one presented in [1]}, because of the missing contributions coming from \(c^{(g)}_{4,0,0,4} I_{4,0,0,-2}\)  and \(c^{(g)}_{4,0,1,3} \mathcal {I}_{4,0,-1,-1} \) .
After adding the latter to the expression of
\(\mathcal {C}^{(1)}_{0 \ n.a.}\)  in [1]}, the resulting combination agrees with our (REF ), therefore implying that the contribution of the massless-scalar double-cut
computed in [1]} agrees with our result. However, as already mentioned above, in [1]} was not included the divergent non-analytic term which scales as \(1/\epsilon \) , and it needs to be treated appropriately with a renormalization procedure.
